MARINE MASTER CLOCK MCS-970 MRC 10121 1999.04 MARINE RADIO CO. LTD. JAPAN

The MARINE MASTER CLOCK MCS-970 (MRC 10121) is a professional-grade, shipboard precision timekeeping instrument manufactured in April 1999 by Marine Radio Co., Ltd. of Japan. It was designed to serve as the primary “Master Clock” for a vessel’s integrated navigation and communication systems, ensuring all equipment is synchronized to a single, accurate time source—a critical requirement for safety, log-keeping, and electronic coordination.

Key Features & Functions

1. Master Clock Function: Its primary role is to generate and distribute precise time signals to slave clocks and other bridge equipment (like GPS, radar, voyage data recorders, etc.), ensuring time uniformity across the entire vessel.
2. Time Source Redundancy & Synchronization:
   • Internal High-Stability Oscillator (SEO): Provides autonomous, accurate timekeeping.
   • External Synchronization Input: Could automatically synchronize to an external time standard, most commonly a GPS receiver (1 PPS signal + serial time data) or a Radio Time Signal Receiver (e.g., JJY, WWV, DCF77). This ensures the clock’s accuracy is maintained at the atomic clock level.
3. Multiple Output Signals: It would have provided various electrical outputs to drive different equipment:
   • Serial Time Data (RS-232/422/485): To update computers and integrated navigation systems (INS).
   • Pulse Per Second (1 PPS): A precise timing pulse for radar and other critical sensors.
   • Slave Clock Drive Signals: (e.g., 24VDC pulses or sine waves) to drive analog and digital secondary clocks throughout the ship (engine room, mess decks, etc.).
   • Time Code Outputs: Possibly IRIG-B or similar for specialized data recorders.
4. Display & Interface:
   • Typically featured a large, bright LED or Fluorescent digital display for clear readability in all lighting conditions.
   • A front-panel keypad or controls for setting UTC (Coordinated Universal Time), local time offsets, and synchronization modes.
   • Status indicators for power, sync source (INT/EXT/GPS), and alarm conditions.
5. Build Quality: Built to withstand the harsh marine environment, conforming to relevant IMO (International Maritime Organization) and IEC (International Electrotechnical Commission) standards for bridge equipment. This includes resistance to vibration, humidity, and electromagnetic interference.

Typical Specifications 

• Manufacturer: Marine Radio Co., Ltd. (MRC), Japan
• Model: MCS-970
• Type: Marine Electronic Master Clock
• Manufacture Date: April 1999 (1999.04)
• Time Base: Suwa Electronic Oscillator (High-Stability Quartz, likely TCXO)
• Accuracy (Internal Oscillator): Approximately ±0.5 to ±2 seconds per month.
• Accuracy (with GPS Sync): Aligned to UTC within microseconds.
• Display: 6- or 8-digit display showing HH:MM:SS (and often date).
• Inputs: Likely 1x GPS antenna input, 1x optional external time signal input.
• Outputs: Multiple isolated outputs for slave clocks, 1 PPS, serial data.
• Power Supply: 24 VDC or 100-230 VAC, standard for shipboard use.

Purpose & Importance on a Vessel

In the late 1990s, as ship bridges were transitioning to integrated electronic systems, the Master Clock was a vital piece of infrastructure. It ensured that:

• Log Books: All events were recorded with a uniform, accurate timestamp.
• Radio Communications: Logs of GMDSS (Global Maritime Distress and Safety System) communications were precise.
• Navigation: Position fixes from GPS, radar plots, and AIS data were correctly time-correlated.
• Safety Investigations: In the event of an incident, data from the Voyage Data Recorder could be accurately sequenced.